Identifying a potential biomarker for primary focal segmental glomerulosclerosis and its association with recurrence after transplantation.

ABSTRACT

BACKGROUND: We investigated circulating levels of individual soluble urokinase plasminogen activation receptor (suPAR) forms to determine if specific circulating fragments of suPAR (II-III) and (I) can better serve as clinical biomarkers for focal segmental glomerulosclerosis (FSGS) and the risk of recurrence after transplantation. MATERIALS AND METHODS: Serum levels of intact suPAR and its cleaved forms were measured with two assays, ELISA and TR-FIA. RESULTS: suPAR levels in healthy controls were significantly lower than those who had glomerular diseases but were not significantly different between FSGS patients and glomerular controls. Intact suPAR (I-II-III) levels were noted to be elevated in glomerular diseases including FSGS. uPAR fragment (I) levels measured with the TR-FIA 4 assay were significantly higher in FSGS (695.4 + 91.29 pMol/L) than glomerular controls (239.1 + 40.45 pMol/L, P = 0.001). However, suPAR(I) levels were not significantly different between recurrent FSGS and nonrecurrent FSGS patients. CONCLUSION: Our analysis of suPAR using the ELISA assay used in all previous studies does not appear to be a useful marker for FSGS nor serve as a predictor for its recurrence after transplantation. The TR-FIA assay results suggest that uPAR(I) is a potential biomarker for FSGS but not of its recurrence.